Aims/Introduction: This study determined the change in prevalence of diabetes and prediabetes over a period of 5 years in South Korea. The incidence of diabetes and prediabetes and risk factors associated with the development of diabetes were also investigated. Materials and Methods: The Dalseong population-based cohort survey recruited 1806 subjects who were over 20-years-old in 2003. Five years later, 1287 of the original subjects were re-evaluated and 187 new subjects were added to the study. All participants completed a questionnaire, were given a physical examination, and provided blood samples for analysis including 2 h oral glucose tolerances. Results: Age-adjusted prevalence of diabetes rose from 6.7% in 2003 to 9.1% in 2008. The prevalence of prediabetes also increased from 18.5% in 2003 to 28.4% in 2008. The incidence rates of diabetes and prediabetes were 18.3 per 1000 person-years and 55.4 per 1000 person-years, respectively. The development of diabetes was associated with impaired fasting glucose (IFG) (odds ratio [OR] 5.661), impaired glucose tolerance (IGT) (OR: 6.013), age (OR 1.013), and waist-to-hip ratio (OR 1.513). After excluding the IFG and IGT, systolic blood pressure (OR 1.023), high-sensitivity C-reactive protein (hsCRP; OR 1.097), triglyceride (OR 1.002) and waist-to-hip ratio (OR 1.696) were statistically significant risk factors in a multivariate logistic regression analysis. Conclusions: A significant rise in the prevalence of diabetes and prediabetes was observed between 2003 and 2008. In addition, this study newly demonstrated that waist-to-hip ratio and hsCRP were associated with the development of diabetes after adjusting for several confounding factors. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2010.00045.x, 2010)